Excuse the horrid quality, I drew it on a whiteboard online. Wolfram got the same exact values for A and B as I got except it produced B = -7/9 and not 7/9 like I did. I don't get what I did wrong here. Any help?

Edit: Never mind our answer's should be equivalent, I was just overlooking the change in signs in the denominator on wolfram when comparing the solution to my own.